Md Jawadur Hi, this is the community forum. If you want to speak directly to bunq, you would need to contact Private Support.
You can find the information about accepted identity documents for German residents (welcome to Germany!) here: https://together.bunq.com/d/43670 As you can see, in order for you to verify your identity and start using bunq, you would need to get an Aufenthaltstitel (German residence permit) as a plastic card. I don't think there's any way around that requirement, but you could of course try to ask Support if there are any other options for you.
and it seems good to me to get a free card and use it on a daily basis
Even after successful identity verification, keep in mind the usage of bunq is not completely free. You can find more information about the available plans on the website: https://www.bunq.com/benefits Even the cheapest plan includes 1 physical card, though, so it's true that you can get a card of your choice for relatively cheap.